Web tension controlling device particularly for use in association with printing machines



Aug. 12, 1958 A. M. HALLEY 2,847,211

WEB TENSION CONTROLLING DEVICE PARTICULARLY FOR USE IN ASSOCIATION WITH PRINTING MACHINES Filed April 16, 1.956

M L W ATTORNEYS United States Patent O T 2,847,211 was TENSION CONTROLLING DEVICE PARTICU- LARLY FOR USE IN ASSOCIATION WITH PRINTING MACHINES Angus Murray Halley, Moseley, Birmingham, England Application April 16, 1956, Serial No. 578,290

Claims. (Cl. 271-2.3)

This invention relates to an improved web tension controlling device for maintaining a substantially constant tension in a web being fed to or from a printing machine or the like, of the kind incorporating a mounted vertically displaceable tensioning roll supported upon a loop portion of the web passing between two idle rollers.

The invention has for its object to provide an improved means for controlling the rate of feed of the web in accordance with the length of web between the idle rollers.

The invention consists of a web tension controlling device of the kind referred to characterized by the provision of a contact arm which is disposed between a-pair of traversably mounted actuating means which are adapted to increase and decrease the rate of feed of the web, the contact arm being adapted to be displaced in a direction dependent on the direction of the vertical displacement of the tensioning roll to thereby operate one or other of the actuating means.

Embodiments of the invention will now be described as applied to the feed of the web to aprinting machine, and for a better understanding of the invention reference will be made to the accompanying drawings wherein:

Fig. 1 illustrates diagrammatically one embodiment of the invention and Fig. 2 illustrates diagrammatically an alternative embodiment of the invention.

The web 1 is fed from a reel 2 through a pair of cooperating -feed rolls 3 and 4, one of the feed rolls 4 being driven by the output shaft 5a of a variable speed gear 5 driven from the main drive (not shown) of the printing machine. The web 1 subsequently passes over a pair of idle rollers 6 and 7 and supports within a loop in the web formed there-between a vertically slidable tensioning roll 8 which is carried by an endless chain 9 passing round a pair of vertically aligned sprockets 10 and 11 and incorporating a counter weight 12 substantially as described in U. S. patent application Serial No. 473,404.

In the embodiment shown in Fig. 1 the upper sprocket 10 drives through a smaller pair of vertically aligned chain sprockets 13 and 14 a pinion 15 meshing with a horizontally traversable rack bar 16 slidable within a pair of supporting brackets 17. It will be understood that according to whether the feed rolls 3 and 4 are feeding more or less web material than is absorbed by the printing machine so the tensioning roll 8 will move down or up and thereby traverse the rack bar 16 to the left or right.

An arm 16a provided intermediate in the length of the rack bar 16 incorporates a pair of oppositely directed contacts 16b located between and co-operable with a pair of oppositely directed micro-valves 18a and 18b secured to a slider 19 which is freely mounted upon a slideway 20. The micro-valves 18a and 18b are adapted for pneumatic or hydraulic operation and are connected by flexible leads 21 to the opposite ends of a double acting cylinder 22, the cylinder being pivotally mounted on the frame of the machine (not shown) and the piston rod 22a therein being connected to the speed control arm 2,847,21 l Patented Aug. 12, 1958 5b of the variable speed gear 5. Adjustment of the distance between the contacts of the micro-valves 18aand 18b is provided to admit of some free movement of the contact arm 16a before operation of the valves in order to prevent hunting, and the rate of movement of the piston of the double acting cylinder 22 may be adjusted by means of a variable throttle device (not shown).

In operation assume initially that the web feed rate is correct when the tensioning roll 8 is disposed midway of its permitted vertical traverse and the contact arm 16a and associated contacts 16b are located centrally between the micro-valves 18a and 18b. If the speed of the web 1 then increases the tensioning roll 8 will descend thereby traversing the rack bar 16 and causing an operation of one of the valves 18a and consequent actuation of the piston in the double acting cylinder 22 in a direction effecting a rotation of the speed control arm 5b of the variable speed gear 5 causing in turn a reduction of the speed of the output shaft 5a thereof and a consequent reduction in the speed of the feed rolls 3 and 4. This speed reduction continues due to the engagement of the contact 16a with the micro-valve 18a, the valves being traversed along the slideway 20 during said engagement, until the web feed rate becomes less than that required by the printing machine. The tensioning roll 8 then. rises and thereby effects the operation and traverse of the alternative micro-valve 13b with a consequent increase in the web feed rate. It will be appreciated that the mechanism will therefore reestablish the tensioning roll 3 in the normal tensioning position and thereby automatically and continuously adjust the peripheral speed of the feed rolls 3 and 4 to admit of the feed rate of the web into the loop being equal within narrow limits to the amount of web being consumed by the printing machine.

Referring to the embodiments of the invention shown in Fig. 2 of the drawings the tensioning roll 8 is arranged substantially as described with reference to Fig. l in so far that it is carried by an endless chain passing over a pair of vertically aligned sprockets l0 and 11. The lower sprocket 11 has secured thereto a smaller sprocket 23 giving say a four to one reduction ratio. The sprocket 23 drives a subordinate endless chain 24 passing round an idle sprocket 25 disposed in horizontal alignment with the sprocket 23. One of the links of the lower run of the chain 24 incorporates a contact arm 24a which is located between and is co-operable with the extended actuating arms 26 of a pair of micro-valves 27 incorporated in the hydraulic or pneumatic circuit of a double acting cylinder 22 in a similar manner to that described with reference to Fig. 1. The micro-valves 27 are secured to a slider 28 freely mounted upon a slideway 29 also in a similar manner to that previously described.

In operation any rise or fall of the tensioning roll 8 consequent upon an increase or decrease in the speed of the Web will result in the traverse of the contact arm 24a into operating contact with one of the alternative microvalves 27 and thereby affect an alteration of the variable speed gear 5 to increase or decrease the peripheral speed of the feed rolls 3 and 4 to automatically and continuously maintain the required tension in the web of material in a similar manner to that described with reference to the embodiment seen in Fig. 1.

It will be appreciated that the fluid operated microvalves 18a and 18b may be replaced by electrical contacts actuation whereof is adapted to control the rotational direction of an electric motor connected to the speed control of the variable speed gear.

In the foregoing description the invention has been described as applied to the control of the tension in a web of paper, it will however be realized that the invention is also applicable to the tension control of many other materials such as for example, textiles, rubber plastics and metal foils.

I claim:

1. A web tension controlling device comprising means for feeding a web of material, power means for varying the speed of the web feeding means, a tensioning roll supported within a loop formed in the web, a contact member, and means for displacing the Contact member in magnitude and direction in proportion to vertical displacement of the tensioning roll comprising a traversably mounted slide carrying a pair of oppositely positioned control members for said power means traversable with said slide, a contact arm having means for moving it in relatively opposite directions in response to vertical displacements of the tensioning roll to operate one or the other of the pair of control members and to impart traversing movement to said slide, and means connected to said power means and operable to increase or decrease the speed of the web feeding means in response to operation of one or the other of said control members by said contact member.

2. A web tension controlling device comprising means for feeding a web of material, power means for varying the speed of the web feeding means, a tensioning roll supported within a loop formed in the Web, a contact member, and means for displacing the contact member in magnitude and direction in proportion to ver'cal displacement of the tensioning roll comprising a slidably mounted rack bar carrying said contact member, a pinion cooperating with the rack bar for reciprocating it, and means for rotating said pinion in accordance with the vertical displacements of the tension roll.

3. A web tension controlling device comprising means for feeding a web of material, power means for varying the speed of the Web feeding means, a tensioning roll supported within a loop formed in the web, a Contact member, and means for displacing the contact member in magnitude and direction in proportion to vertical displacement of the tensioning roll comprising a slidably mounted rack bar carrying said contact member, a pinion cooperating with the rack bar for reciprocating it, a chain and sprockets for operating said pinion, an endless chain carrying the tensioning roll and having sprockets one of which is larger than and is connected to one of the first-mentioned sprockets, and a pair of control members for the power means having oppositely positioned actuating members operable respectively by said contact member in response to displacements thereof in opposite directions.

4. A web tension controlling device comprising means for feeding a Web of material, power means for varying the speed of the web feeding means, a tensioning roll supported within a loop formed in the web, a contact member traversable in relatively opposite directions, and means for displacing the contact member in magnitude and direction in proportion to vertical displacement of the tensioning roll comprising a chain having means for driving it in ratio and direction in accordance with vertical displacements of the tensioning roll and carrying said contact member, a pair of control members for the power means having actuating means operable in response to movement of the contact member in one or the other direction respectively, and means connecting the power means to said control members and operable to increase or decrease the speed of the web feeding means in response to displacement of the contact member in one or the other direction.

5. A web tension controlling device comprising means for feeding a web of material, power means for varying the speed of the web feeding means, a tensioning roll supported within a loop formed in the web, a contact member traversable in relatively opposite directions, and means for displacing the contact member in magnitude and direction in proportion to vertical displacement of the tensioning roll comprising a chain having means for driving it in ratio and direction in accordance with vertical displacements of the tensioning roll and carrying said contact member, a pair of sprockets around which said chain passes, a pair of vertically aligned sprockets one of which drives one of the sprockets of said pair around which said chain carrying said contact member passes, and an endless chain meshing with said vertically aligned sprockets and carrying the'tensioning roll.

References Cited in the file of this patent UNITED STATES PATENTS 2,214,609 Drake Sept. 10, 1940 2,317,921 Leach Apr. 27, 1943 2,517,861 Franklin Aug. 8, 1950 FOREIGN PATENTS 709,449 Germany Aug. 16, 1941 

